Hot-water tank connection



0. E. ANDRUS HOT WATER TANK CONNECTION May 31, 1949.

Filed Feb. 10, 1947 Patented May 31, 1949 HOT-WATER TANK CONNECTION Orrin E. Andrus, Altadena, Calif., assignor to A. 0. Smith Corporation, Milwaukee, Wis., a

corporation of New York Application February 10, 1947, Serial No. 727,538

6 Claims.

This invention relates to a connection for domestic hot water heater storage tanks and the like which are lined with a protective coating such as ceramic enamel to protect the tank from corrosion by contained fluid.

The principal object of the invention is to provide a hot water tank connection which will not set up stresses in the tank injurious to the corrosion resistant protective coating.

Another object of the invention is to provide a spud connection for a hot water tank Which may be easily manufactured and welded or brazed to the outside of the tank.

A further object of the invention is to provide a spud connection for a hot water tank, the shape of which prevents the building up of destructive stresses in the enamel coating.

Another object of the invention is to provide a hot water tank spud connection which absorbs stresses in service when an element is threaded therein, to prevent injury to the enamel at the joint between the spud and tank wall.

These and other objects of the invention will appear hereinafter in connection with the following description of an embodiment of the invention illustrated in the accompanying drawmg In the drawing:

Figure 1 is a longitudinal section of a portion gf a hot water tank showing the spud connec- Fig. 2 is an inner end View of Fig. 1 on a reduced scale; and

Fig. 3 is an outer end view of Fig. 1 on a reduced scale.

Referring to the drawing, there is shown a portion of the shell I of a hot water tank which has an opening 2 at which is disposed the tubular member or spud 3 providing the connection for the tank. Spud 3 is of corrosion resistant stainless steel and the inside of the tank shell is lined with a protective coating such as ceramic enamel 4. to protect the metal of the tank from corrosion by contained fluid.

Spud 3 is generally circular in shape and comprises a relatively thick body portion 5 and an annular supporting base 6 which are connected by a neck portion 1 of substantially lesser crosssection radially than either the body or base of the spud.

The outer circumference of base 6 tapers to a generally thin flange preferably corresponding to the thickness of shell I and provides a substantial surface area on the base for securing the spud to the outside of the shell around opening 2.

The inside of spud 3 is formed with the annular groove or depression 8 between base 6 and body 5 to form the generally thin neck 1 therebetween and provide base 6 with the generally thin inward flange 9 on the inner circumference thereof. Flange 9 also preferably corresponds in thickness to that of shell I.

Body 5 of the spud is internally threaded for connecting a pipe H) or other element thereto and the threaded opening therein is of smaller diameter than the opening 2 of shell I' and than the corresponding opening in flange 9 so that pipe Hi can be threaded through the spud without engaging the edge of the opening.

Spud 3 is secured to the outside of shell I by braze metal ll such as copper which is disposed in the joint between the base of the spud and the outside of shell I. The spud may also be joined to the tank by electric resistance welding.

Shell l is provided with ceramic enamel 4 after spud 3 is secured thereto. In the enameling operation enamel 4 is extended across the joint between the shell and spud at opening 2 to protect the brazing metal and the metal of the shell from corrosion at the joint area. In order to provide a good enameling surface the sharp inner corners of the shell at opening 2 and of flange 9 are rounded off as at I2.

The enameling temperatures employed are substantially lower than the temperatures at which braze metal I l melts so that the latter will not be injured in the enameling operation.

In constructing and assemblin the spud connection described shell I is first fabricated of generally cylindrical shape from suitable carbon steel and is provided with opening 2 to accommodate spud 3. The inner corner at opening 2 is then rounded off as at l 2 to prepare the shell for enameling.

Spud 3 is preferably cast with the base 6 of a shape to fit the shell around opening 2 and the base 6 is connected to the generally thick outwardly projecting body portion 5 thereof by the neck 1 of lesser cross-section radially than the base and body of the spud.

In making the spud it is important to employ a stainlesssteel that has a coefiicient of expansion similar to that of the coefiicient of expansion of the carbon steel of shell I.

Base 6 is then assembled against the outside of shell 8 around opening 2 and the spud is tightly held or clamped to the shell. Braze metal H is provided in the joint between the shell and spud and the structure is then heated to a brazing temperature such as 1700 F. to braze the spud and shell together in a suitable atmosphere such as hydrogen.

Thereafter ceramic enamel 4 is applied and fused to the interior surface of shell I and across the joint between the spud and shell at opening 2. The spud is then ready to receive the pipe connection I9 which is threaded into body 5 thereof without engagement with the edges 'of opening 2,

By providing a generally thin neck 1 between the base and body of the spud through employment of a depression or groove .8 on the inside of the spud the generally thin flange '9 is disposed at the shell opening and relieves stresses between the spud and shell during "cooling aT-ter firing of the enamel since flange 9 and the tank shell are of substantially the same thickness and will cool at about the same rate.

Similarly the tapered flange at the outer circumference of the spud relieves stresses at that area in the cooling of the shell and spud after enameling due to the corresponding gradually reduced thickness in the shell and spud.

The substantial area of the joint between base 5 and shell l provides a distribution of stresses between the same sufficient to prevent destructive concentrations ofstress in the enamel.

Neck 1 also constitutes a heat dam which permits the base of the spud to cool at substantially the same rate as shell l without being affected by the thicker body 5 of the spud.

By providing a spud connection which is formed to prevent the building up-of stresses, the enamel or other protective coating employed is protected against injury at the tank opening.

In addition the construction of the body of the spud of lesser diameter than the tank opening eliminates possibility of injury to the protective lining of the tank at opening 2 when a pipe or other element is threaded into the spud.

Various embodiments of the invention may be employed within the scope of the accompanying claims. 1

I claim:

1. A connection for an opening in a hot water storage tank or the like lined with a protective coating on the inside of the tank wall to protect the tank from corrosion, which comprises a tubul'ar spud on the outside of the tank wall of corrosion resistant metal disposed at said opening and bonded to the outside of the tank around said opening, said spud comprising a base portion overlapping the outside of the tank wall radially outwardly from the opening therein for a substantial distance and joined to a relatively thicker body portion by a neck of substantially lesser cross-section circumferentially than said base and body portion to provide the base with inner and outer flanges of tapered thickness and prevent the building up of stresses at the joint between the spud and shell injurious to the protective lining of the tank.

2. A connection for an opening in a hot water storage tank or the like lined with a protective coating on the inside of the tank wall to protect the tank from corrosion, which comprises a tubular spud on the outside of the tank wall of cor rosion resistant metal disposed at said opening with a body disposed to receive a connecting element and a base bonded to the outside of the tank around said opening, and a generally thin neck portion disposed between the body and base of said spud to provide aflange overlapping the outside of the tank wall radially outwardly from the opening therein for a substantial distance and a heat dam between the flange and body.

3. A connection for an opening in a hot water storage tank or the like lined with ceramic enamel to protect the same from corrosion, which comprises a tubular spud of corrosion resistant metal disposed at said opening and secured to the outside of the tank around said opening, said spud having an annular groove in the inside thereof around said tank opening to provide a generally thin flange on the spud overlapping the outside of the tank wall radially outwardly from the opening therein for a substantial distance to relieve the stresses the spud and prevent injury to the enamel adjacent the opening upon cooling of the spud and tank after enameling of the tank.

4. A connection for an opening in a hot water storage tank or the like lined with a protective coating on the inside of the tank wall to protect the tank from corrosion, which comprises a tubular spud on the outside of the tank wall of corrosion resistant metal disposed at said opening and bonded to the outside of the tank around the opening, a generally thin tapered flange on the outer circumference of said spud overlapping the tank wall for a substantial distance, and an annular groove extending inside of said spud around the tank opening to provide a generally thin flange on the inner circumference of the spud overlapping the outside of the tank wall radially outwardly from the opening therein for a substantial distance, and said flanges serving to relieve stresses between the spud and tank upon cooling after heating during application of the protective lining and to provide a substantial bonding surface between the spud and shell.

5. A connection for an opening in a hot water storage tank or the like lined with a protective coating on the inside of the tank wall to protect the tank from corrosion, which comprises a tubular spud on the outside of the tank wall of corrosion resistant metal disposed at said opening and bonded to the outside of the tank around the opening, a generally thin tapered flange on the outer circumference of said spud overlapping the tank Wall for a substantial distance, and an annular groove extending inside of said spud around the tank opening to provide a generally thin flange on the inner circumference of the spud overlapping the outside of the tank wall radially outwardly from the opening therein for a substantial distance, said flanges serving to relieve stresses between the spud and tank upon cooling after heating during application of the protective lining and to provide a substantial bonding surface between the spud and shell, the body of said spud being spaced from said flanges by a relatively thin neck section extending outwardly from between said flanges, and the body having a threaded opening therein axially of the opening through the tank wall and through the inner flange of the spud and of smaller diameter than said latter opening for receiving a pipe connection or the like without contact between the pipe and the tank wall and inner flange.

6. A connection for an opening in a hot water storage tank or the like lined with ceramic enamel to protect the same from corrosion, which oomprises a tubular spud of corrosion resistant metal disposed in axial alignment with said opening secured to the outside of the tank around the opening with the threaded central opening through the spud being of lesser diameter than the opening in said tank, said spud having an annular 2,471,475 H 5 6 v groove extending on the inside of the spud around REFERENCES CITED said tank opening and axially inwardly removed from the threaded portion of said spud, said groove providing a generally thin flange on the The following references are of record in the file of this patent:

spud overlapping the outside of the tank wall 5 UN TED STATES PATENTS radially outwardly from the opening in the tank Number Namm Date for a substantial distance to relieve stresses in the 881,045 Badger Man 3 1908 spud and prevent injury to the enamel adjacent 1,120,048 Glass the opening upon cooling of the spud and tank 2,013,683 Meyer 061129, 1935 after enameling of the tank and also upon thread- 10 2,243,164 Maddock May 27 1941 ing of a connection into the spud.

ORRIN E. ANDRUS. 

